[libvirt] [RH-BZ #595428] 'virsh list' should output more information 'xm list'

[Maxim Sditanov]

2012/4/19 dennis jenkins <dennis.jenkins.75 at gmail.com>:
>
>
> On Thu, Apr 19, 2012 at 10:25 AM, Maxim Sditanov <feniksa at rambler.ru> wrote:
>>
>> 2012/4/2 Maxim Sditanov <feniksa at rambler.ru>:
>> > Is this new feature request still
>> > https://bugs.gentoo.org/show_bug.cgi?id=366561 actual?
>> >
>> > Because virsh still show not enough information:
>> >
>> > $./virsh -c qemu:///system list --all
>> >
>> >  Id    Name                           State
>> > ----------------------------------------------------
>> >  1     "                                running
>> >  -     winxp                          shut off
>> >
>> > And it will be good idea to show more detailed information or add
>> > additional flag, something like --detail.
>> > ./virsh -c qemu:///system list --all --detailed
>> >
>> >
>> > Id Name       State        Memory   VCPU     Uptime    CPU   IOPS
>> > ----------------------------------
>> > -------------------------------------------------------------
>> >  1  "            running        768M      2         3hours     5%
>> >  12.1
>> >  -  winxp      shut off        512M      1
>> >
>>
>> I implemented first part of this task - VCPU and CPU load.
>> I ported from virt-manager CPU load algorithm
>> (thanks Cole Robinson for help
>> https://www.redhat.com/archives/virt-tools-list/2012-April/msg00051.html)
>>
>> virt manager update graphic in such way:
>> It create thread, than it take host CPU ticks (how much cpu time take
>> host)
>> then every 1 sec it update value and calculate percentage.
>> But this algorithm is bad in virsh, because virsh give information about
>> domains imidiatly, without delays and thats why i can't caclulate cpu
>> (also io and
>> network usage).
>>
>> I think it will be good idea if libvirtd will hold information about
>> resource usage and implement interface for this data via libvirt
>> And virsh and virt-manager will use
>> the same functions to get cpu, disk and network usage, host uptime
>>
>> How do you think?
>
>
> (disclaimer: I'm not a libvirt contributor, just a consumer.  Do I get to
> vote? :) )

I am not libvirt core team developer, i am just volunteer :-)

> If statistics collection is implemented directly in libvirtd, how often
> would libvirtd capture these statistics?  Once per second? 10s, 1m, etc...?

Libvirt manager update graphics every 1 second. I think it is good idea to
allow configure how offen ilbvirtd will update statistic

> Would the interval be user-configurable (per-VM)?  If so, could this setting
> be changed on the fly (eg, to a live VM and effective immediately)?
>
> Would the statistics survive a restart of libvirtd?  If so, how would they
> be persisted (flat text, xml, sqlite database)?

I didn't think about this yet. But it is reasonable to hold statistic
after libvirtd
restart (or crash). But i didn't examine libvirtd yet

> How far back would the stats be kept for?  Would this value be configurable
> per-VM?
>
> +1.  I would like to get these kind of stats from "virsh list", and very
> much like to get CPU and IO usage history from libvirtd.  I'm developing a
> simple web interface for managing QEMU and LXC via libvirt (apache,
> mod_perl, Sys-Virt, sqlite3, noVnc) for personal use.  I know that libvirt
> can give CPU and IO usage info, but not historic info suitable for
> assembling a quick graph.  If libvirtd cannot provide historic info, then I
> will need to implement a separate daemon to record it, probably by polling
> libvirtd at synchronous intervals.

Also, it is not trivial to get cpu percentage usage (because you need to make
calculation). And virsh, virt-manager and other 3-ty pard software
will implement
the same percentage calculation algorithm. I think, it is better to
hold such things in
one place

> side-note: I should put up a web page with screen-shots of my work in
> progress, and provide access to my source code (personal SVN server).  Does
> anyone here have an interest in using or examining my little project?

I am interesting, just email me directly :-)

> ps- I didn't mean to hijack your thread.  I just wanted to state my desire,
> as a user of libvirt, to have this functionality (however tenuously defined)
> in place.

No problem

> Thank you guys and gals for making libvirt excellent.  I've notice the
> quality of the feedback given to submitted patches and am impressed.
>
> --
> libvir-list mailing list
> libvir-list at redhat.com
> https://www.redhat.com/mailman/listinfo/libvir-list

But i still need comments from libvirt core team about such improvement
and advice

Thanks

-- 
With best wishes, Feniks Gordon Freeman